The present invention relates to agricultural implements, and more specifically relates to such implements as have rotational components located remotely from an operator""s station associated either with the implement itself or with a vehicle towing the implement.
The functional elements of agricultural crop harvesters include some that are relatively massive and driven in rotation. When the power for driving these components is disconnected by an action of the operator, the operator is apt to believe that the rotation of the component has stopped, when in fact, the inertia of the component causes it to continue to rotate. This rotation will sometimes continue for several minutes, which is beyond the time that it takes for an operator to leave the operator""s station and remove shielding extending about, or open an access door of a housing containing, the component, thus exposing the operator to danger.
U.S. Pat. No. 4,843,767 discloses one example of a harvester having rotating components which are remotely controlled by an operator and which may possibly operate so as to give rise to the above-described problem.
U.S. Pat. No. 4,974,711 discloses a brake and clutch control system for the power take-off of a lawn and garden tractor that may be equipped with a mower coupled to the tractor power take-off. The control system may embody a seat switch that acts to cause the power take-off control clutch to be disengaged and the brake to be engaged in the event that the operator leaves the seat. While such a system ensures that the operator will not accidentally come into contact with the rotating mower blades, a practical system for reliably stopping the spin down of large inertia components is not yet available.
U.S. Pat. No. 5,132,327 discloses a control system for warning an operator of the continued rotation of a spindle for a machine, such as a wood working machine, due to the inertia of the spindle after a motor for rotating the spindle is shut off. In this control system, the location of the operator is not taken into account and the warning device is a light which is normally lit when the drive motor is operating so the operator may not pay attention to it after the power to the motor is discontinued.
According to the present invention, there is provided an improved warning system for use with agricultural implements embodying rotatably driven components, for example, forage harvesters, combines, cotton harvesters and the like.
An object of the invention is to provide a warning system, incorporated in the component drive control system, so as to reduce the likelihood of an operator coming into contact with a rotating component of the implement after the operator has disconnected the power to the component.
A more specific object of the invention is to provide an electrical safety interlock circuit which includes an operator presence sensor and a component rotation sensor having respective outputs coupled to a circuit for controlling operation of a warning device, the circuit operating to activate the warning device if the operator, after disengaging power to the rotating component, leaves the operator""s seat while the component is still rotating.
Yet a more specific object of the invention is to provide a safety interlock circuit, as stated in the immediately preceding object, wherein a count-up timer device is provided which prevents actuation of the warning device in the event that the operator leaves the operator seat only momentarily.
Another specific object of the invention is to provide a safety interlock circuit, as stated in one or more of the preceding objects, wherein the circuit contains a timer circuit which times out to cause the warning device to be turned off only upon the expiration of a time sufficient for the rotating component to spin down.
A further object of the invention is to provide a safety interlock circuit, as stated in one or more of the preceding objects, wherein the warning device is kept from being activated when the circuit receives a signal indicative of the operator intentionally selecting a mode of powered operation before leaving the operator seat.
These and other objects of the invention will become apparent from a reading of the ensuing description together with the appended drawings.